Every time you Command-Tab, your brain treats it as walking through a door. The literature on the doorway effect says that crossing an event boundary flushes some of the state you were holding a second earlier. On a modern Mac, you cross fifty of those boundaries a day. That's not a productivity metaphor. It's a specific finding about how the brain segments time.

Csikszentmihalyi's flow research identifies "freedom from interruption" as a precondition for flow, not a nice-to-have. On a Mac managing multiple projects, that precondition is mostly an environment problem: which apps, tabs, and notifications are visible when you sit down. Here is how to engineer that environment instead of relying on an AI tool to detect flow after the fact.

AI focus-tracking apps infer concentration from keystrokes, app switching, and screen content - which is a real data-handling question the moment you work across multiple clients on one Mac. Here is what these tools actually collect, and why a context-based approach that never looks at your screen solves the underlying focus problem without the exposure.